scholarly journals A Medley of Midbrain Maladies: A Brief Review of Midbrain Anatomy and Syndromology for Radiologists

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Kathleen Ruchalski ◽  
Gasser M. Hathout
Keyword(s):  
White Matter ◽  
Red Nucleus ◽  
Cranial Nerves ◽  
White Matter Tracts ◽  
Nuclear Complex ◽  
Radiologic Findings ◽  
Fiber Tracts ◽  
Clinical Syndromes ◽  
Brachium Conjunctivum ◽  
Trochlear Nucleus

The midbrain represents the uppermost portion of the brainstem, containing numerous important nuclei and white matter tracts, most of which are involved in motor control, as well as the auditory and visual pathways. Notable midbrain nuclei include the superior and inferior colliculus nuclei, red nucleus, substantia nigra, oculomotor nuclear complex, and trochlear nucleus. In addition, white matter tracts include the brachium conjunctivum, medial and lateral lemniscus, spinothalamic tracts, and the fiber tracts within the cerebral peduncles. Although neurologically vital, many of these small midbrain nuclei and white matter tracts are not easily individually identified on neuroimaging. However, given their diverse functions, midbrain pathology often leads to distinct clinical syndromes. A review and understanding of the location and relationships between the different midbrain nuclei and fiber tracts will allow more precise correlation of radiologic findings with patient pathology and symptomatology. Particular syndromes associated with midbrain pathology include the Weber, Claude, Benedikt, Nothnagel, and Parinaud syndromes. The oculomotor and trochlear cranial nerves also reside at this level. An understanding of their functions as well as their projected courses from the midbrain towards the eye allows identification of distinct locations which are particularly vulnerable to pathology.

Anatomy and White Matter Connections of the Superior Parietal Lobule

2021 ◽  
Author(s):  
Yueh-Hsin Lin ◽  
Nicholas B Dadario ◽  
Jorge Hormovas ◽  
Isabella M Young ◽  
Robert G Briggs ◽  
...  
Keyword(s):  
White Matter ◽  
Ground Truth ◽  
Superior Parietal Lobule ◽  
White Matter Tracts ◽  
Anatomical Dissection ◽  
Diffusion Spectrum Imaging ◽  
Fiber Tracts ◽  
Important Region ◽  
Human Connectome Project ◽  
Parietal Lobule

Abstract BACKGROUND The superior parietal lobule (SPL) is involved in somatosensory and visuospatial integration with additional roles in attention, written language, and working memory. A detailed understanding of the exact location and nature of associated white matter tracts could improve surgical decisions and subsequent postoperative morbidity related to surgery in and around this gyrus. OBJECTIVE To characterize the fiber tracts of the SPL based on relationships to other well-known neuroanatomic structures through diffusion spectrum imaging (DSI)-based fiber tracking validated by gross anatomical dissection as ground truth. METHODS Neuroimaging data of 10 healthy, adult control subjects was obtained from a publicly accessible database published in Human Connectome Project for subsequent tractographic analyses. White matter tracts were mapped between both cerebral hemispheres, and a lateralization index was calculated based on resultant tract volumes. Post-mortem dissections of 10 cadavers identified the location of major tracts and validated our tractography results based on qualitative visual agreement. RESULTS We identified 9 major connections of the SPL: U-fiber, superior longitudinal fasciculus, inferior longitudinal fasciculus, inferior fronto-occipital fasciculus, middle longitudinal fasciculus, extreme capsule, vertical occipital fasciculus, cingulum, and corpus callosum. There was no significant fiber lateralization detected. CONCLUSION The SPL is an important region implicated in a variety of tasks involving visuomotor and visuospatial integration. Improved understanding of the fiber bundle anatomy elucidated in this study can provide invaluable information for surgical treatment decisions related to this region.

Brainstem and Cranial Nerves: Midbrain

2021 ◽  
pp. 92-98
Author(s):  
Kelly D. Flemming ◽  
Paul W. Brazis
Keyword(s):  
Substantia Nigra ◽  
Red Nucleus ◽  
Cranial Nerves ◽  
Posterior Commissure ◽  
Middle Cerebellar Peduncle ◽  
Mammillary Bodies ◽  
Imaginary Line ◽  
Cerebellar Peduncle ◽  
Trochlear Nucleus ◽  
Inferior Colliculi

The midbrain (or mesencephalon) is the uppermost segment of the brainstem. This chapter reviews the important structures in the midbrain, including cranial nerves III and IV. The midbrain extends from the level of the trochlear nucleus to an imaginary line between the mammillary bodies and the posterior commissure. Important structures at this level include the cerebral peduncles, superior and inferior colliculi, red nucleus, substantia nigra, decussation of the middle cerebellar peduncle, and cranial nerves III and IV.

scholarly journals Dorsal-to-ventral imbalance in the superior longitudinal fasciculus mediates methylphenidate’s effect on beta oscillations in ADHD

2020 ◽  
Author(s):  
C. Mazzetti ◽  
C. G. Damatac ◽  
E. Sprooten ◽  
N. ter Huurne ◽  
J.K. Buitelaar ◽  
...  
Keyword(s):  
White Matter ◽  
Diffusion Tensor ◽  
Structural Connectivity ◽  
Superior Longitudinal Fasciculus ◽  
Beta Oscillations ◽  
Double Blind ◽  
Attention Task ◽  
White Matter Tracts ◽  
Fiber Tracts ◽  
Beta Power

AbstractBackgroundWhile pharmacological treatment with Methylphenidate (MPH) is a first line intervention for ADHD, its mechanisms of action have yet to be elucidated. In a previous MEG study, we demonstrated that MPH in ADHD normalizes beta depression in preparation to motor responses (1). We here seek to identify the white matter tracts that mediate MPH’s effect on beta oscillations.MethodsWe implemented a double-blind placebo-controlled crossover design, where boys diagnosed with ADHD underwent behavioral and MEG measurements during a spatial attention task while on and off MPH. Results were compared with an age/IQ-matched typically developing (TD) group performing the same task. Estimates of white matter tracts were obtained through diffusion tensor imaging (DTI). Based on aprioristic selection model criteria, we sought to determine the fiber tracts associated with electrophysiological, behavioral and clinical features of attentional functions.ResultsWe identified three main tracts: the anterior thalamic radiation (ATR), the Superior Longitudinal Fasciculus (‘parietal endings’) (SLFp) and Superior Longitudinal Fasciculus (‘temporal endings’) (SLFt). ADHD symptoms severity was associated with lower fractional anisotropy (FA) within the ATR. In addition, individuals with relatively higher FA in SLFp compared to SLFt showed faster and more accurate behavioral responses to MPH. Furthermore, the same parieto-temporal FA gradient explained the effects of MPH on beta modulation: subjects with ADHD exhibiting higher FA in SLFp compared to SLFt also displayed greater effects of MPH on beta power during response preparation.ConclusionsBased on MPH’s modulatory effects on striatal dopamine levels, our data suggest that the behavioral deficits and aberrant oscillatory modulations observed in ADHD depend on a structural connectivity imbalance within the SLF, caused by a diffusivity gradient in favor of temporal rather than parietal, fiber tracts.

scholarly journals Advanced white matter mapping in the subconcussive brain

Neurology ◽  
2018 ◽  
Vol 91 (23 Supplement 1) ◽  
pp. S15.2-S15
Author(s):  
Bradley Caron ◽  
Nicholas Port ◽  
Franco Pestilli
Keyword(s):  
White Matter ◽  
Structural Changes ◽  
Diffusion Tensor ◽  
Division I ◽  
Football Players ◽  
Tensor Model ◽  
White Matter Tracts ◽  
Tissue Properties ◽  
Research Fields ◽  
Fiber Tracts

The topic of behavioral and structural deficits caused by concussions is an increasingly important 1 in the related research fields. With an incidence rate of 2.9 competition concussions per 1,000 athlete exposures (NCAA 2013) in collegiate football, the concussion risk to athletes is significant. However, even subconcussive blows, or blows that do not lead to a concussion diagnosis, appear to create health risks for athletes. These impacts appear to lead to significant neural changes, the severity of which may depend on the number of hits (McAllister et al., 2014). An anatomically informed, personalized-medicine tractography approach was used to determine which major white matter tracts showed the greatest degree of difference in white matter tensor measures between 17 Division I upperclassmen football players, 15 Division I upperclassman cross-country runners, and 9 socioeconomically-matched non-athlete controls. We determined the underlying microstructural white matter biomarkers, using a classic diffusion-tensor model (Pierpaoli and Basser, 1999) as well as Neurite Orientation Dispersion and Density Imaging (NODDI; Zhang et al., 2012), that predict differences across different white matter tracts in the groups of athletes. Results show widespread differences in white matter tissue properties in multiple tracts and among the 3 athletes groups, including decreased FA, increased ICVF, and OD in the football players vs the 2 control groups. These differences occurred more often in longer fiber tracts compared to shorter fiber tracts, suggesting a differential effect of head impacts based on the geometric properties of these tracts. We developed a fully automated processing pipeline for this study, available as open source code as well as open service at brainlife.io. These results support the hypothesis that multiple subconcussive blows can result in white matter structural changes, with differential effects based on the length of the fiber tract being investigated, that are detectable with diffusion MRI and tractography.

Age-depending degeneration of white matter tracts – A DTI-Study

2010 ◽  
Vol 41 (01) ◽  
Author(s):  
J Faber ◽  
JC Schöne-Bake ◽  
C Melzer ◽  
M Tittgemeyer ◽  
B Weber
Keyword(s):  
White Matter ◽  
White Matter Tracts

Individual differences in white and grey matter structure associated with verbal habits of thought

2019 ◽  
Author(s):  
Justin C. Hayes ◽  
Katherine L Alfred ◽  
Rachel Pizzie ◽  
Joshua S. Cetron ◽  
David J. M. Kraemer
Keyword(s):  
Individual Differences ◽  
White Matter ◽  
Cognitive Processing ◽  
Grey Matter ◽  
Structural Changes ◽  
Structural Integrity ◽  
Diffusion Tensor ◽  
Self Report ◽  
White Matter Tracts

Modality specific encoding habits account for a significant portion of individual differences reflected in functional activation during cognitive processing. Yet, little is known about how these habits of thought influence long-term structural changes in the brain. Traditionally, habits of thought have been assessed using self-report questionnaires such as the visualizer-verbalizer questionnaire. Here, rather than relying on subjective reports, we measured habits of thought using a novel behavioral task assessing attentional biases toward picture and word stimuli. Hypothesizing that verbal habits of thought are reflected in the structural integrity of white matter tracts and cortical regions of interest, we used diffusion tensor imaging and volumetric analyses to assess this prediction. Using a whole-brain approach, we show that word bias is associated with increased volume in several bilateral language regions, in both white and grey matter parcels. Additionally, connectivity within white matter tracts within an a priori speech production network increased as a function of word bias. These results demonstrate long-term structural and morphological differences associated with verbal habits of thought.

Microstructural differences in visual white matter tracts in people with aniridia

Neuroreport ◽  
2018 ◽  
Vol 29 (17) ◽  
pp. 1473-1478 ◽  
Author(s):  
Courtney R. Burton ◽  
David J. Schaeffer ◽  
Anastasia M. Bobilev ◽  
Jordan E. Pierce ◽  
Amanda L. Rodrigue ◽  
...  
Keyword(s):  
White Matter ◽  
White Matter Tracts
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